1. Field of the Invention
The present invention relates to the field of displaying, and in particular to a method for manufacturing a light-shielding mask for curing a cell sealant.
2. The Related Arts
A cell sealant is an adhesive used in a liquid crystal display panel for bonding two glass substrates of a thin-film transistor array substrate and a color filter substrate to prevent a liquid crystal material filled between the two glass substrate from leaking out. Referring to FIG. 1, a schematic view is given to show the structure of a conventional liquid crystal display pane, in which a cell frame 100 is formed by curing a cell sealant.
A conventional process first forms spacers on a surface of an alignment film and then uses the cell sealant to bond the glass substrates to form an empty liquid crystal cell. Later, with the size of the panel changing in a direction toward enlarged ones, the percentage of application of ODF (One Drop Filling) process is increased so that certain changes are made on the manufacturing process and the properties of the cell sealant also change.
The cell sealants are generally divided into two types, namely heat curing sealants and UV (Ultra-Violet) curing sealants. The conventional ODF process generally use the UV curing sealants. Due to the fact that the ODF processes are commonly adopted in new manufacturing lines, the UV curing sealants would become the main-stream sealants. The components of a UV curing sealant includes a photo initiator and a UV bonding agent. When the photo initiator absorbs UV, the photo initiator is caused to generate free radicals and cation reactive radicals. These free radicals or cation radicals, which are generally of high reactivity, may participate in chain extension reactions with acrylic unit or epoxy unit and the corresponding oligomers that are contained in the composition. Since the reactivity of the free radical reaction or the cation radical reaction is very fast, these reactants can complete the reaction in few seconds to few minutes and a polymer having desired properties is formed. The characteristics of the UV bonding agent may initiate a chemical chain reaction through the radiation of UV light in order to cure the sealant. A cured bonding substance can be formed in few seconds.
By irradiating UV light on the entirety of a liquid crystal display panel would result in property variation of some material components that constitute the panel and the performance of the material is affected so that, eventually, the quality and yield rate of the liquid crystal display panel are affected. Thus, it is a common practice that UV irradiation and UV curing are selectively applied to the sealant and light is shielded with a light-shielding plate in the area where no UV irradiation is necessary. Such a function can be realized with a light-shielding mask. Referring to FIG. 2, a light-shielding mask generally comprises: a pattern section 300 and a light-shielding section 500 set along an outer circumference of the pattern section 300. To carry out UV curing of the sealant of a liquid crystal display panel, UV light is allowed to pass through the pattern section 300 to irradiate the sealant to cure the sealant, while the light-shielding section blocks out the UV light, preventing the UV light from irradiating other materials of the liquid crystal display panel and causing variation of properties of the materials.
The location where the sealant may be applied is different for liquid crystal display panels of different sizes and different models. This makes it necessary to provide light-shielding plates of different sizes and different models to correspond to liquid crystal display panels of different sizes and different models.
Referring to FIGS. 3-6, a conventional process for manufacturing a light-shielding mask for curing a sealant is generally as follows. A metal layer 702 and a photoresist layer 704 are first coated on a substrate 700. Then, a masking plate 750 is applied to form a predetermined pattern on the photoresist layer 704 through exposure. Development, etching, and photoresist peeling are then carried out. Finally, a non-metallic protection layer 706 is coated on the pattern so formed. In this process, for exposure of the photoresist layer 704, the masking plate 750 must be provided with a pattern that is exactly the same as the predetermined pattern to be formed. This makes it necessary to provide different masking plates for manufacturing light-shielding masks of different sizes and different models for curing sealants. In other words, for each side and each model of the light-shielding plate for curing a sealant, there must be at least one masking plate corresponding thereto so that the manufacture cost is high and unified management may not be suitable.